package org.apidesign.api.security;

 import java.nio.ByteBuffer;

 import java.util.ServiceLoader;

 import org.apidesign.spi.security.Digestor;

 /** Simplified version of a Digest class that allows to compute a fingerprint

  * for buffer of data.

  *

  * @author Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  */

 // BEGIN: day.end.bridges.Digest

 public final class Digest {

     private final DigestImplementation<?> impl;

     /** Factory method is better than constructor */

     private Digest(DigestImplementation<?> impl) {

         this.impl = impl;

     }

     /** Factory method to create digest for an algorithm.

      */

     public static Digest getInstance(String algorithm) {

         for (Digestor<?> digestor : ServiceLoader.load(Digestor.class)) {

             DigestImplementation<?> impl = DigestImplementation.create(digestor, algorithm);

             if (impl != null) {

                 return new Digest(impl);

             }

         }

         throw new IllegalArgumentException(algorithm);

     }

     //

     // these methods are kept the same as in original MessageDigest,

     // but for simplicity choose just some from the original API

     //

     public byte[] digest(ByteBuffer bb) {

         return impl.digest(bb);

     }

 }

 // END: day.end.bridges.Digest